1. Technical Field of the Invention
The present invention relates to a vehicle driving assistance device that sets a steering angle such that a vehicle runs properly based on a recognized lane line.
2. Related Art
Nowadays, with the progress of electronics technologies, various driving assistance devices are developed and put to practical use in vehicles. Some of the driving assistance devices recognize a lane line with a camera mounted on a vehicle, estimate a traveling route of a subject vehicle, and add a predetermined steering force or perform automatic steering based on the estimated traveling route.
For example, The Japanese Unexamined Patent Application Publication No. 2007-8281 discloses a technique that performs lane maintaining control based on a detected lane line and a virtual lane line. More specifically, when an obstacle is detected, the lane maintaining control is performed to set the virtual lane line within the travelling lane inwardly from the obstacle based on a distance from the subject vehicle to the obstacle.
In this kind of driving assistance device, desirably not only vehicle external information ahead of a subject vehicle but also vehicle external information behind the subject vehicle are sufficiently considered in order to perform the driving assistance control fitting to a driver's feeling. However, if an image of vehicle external environment is captured to recognize the lane line with respect to environment behind the subject vehicle similarly to the environment ahead of the subject vehicle, the structure or processing of the device may be complicated.